In a working vehicle such as a wheel loader, it has typically been known to provide a ladder for an operator to climb up and down in order to move between the ground and an engine compartment (see, for instance, Patent Literature 1). Such a ladder is provided posterior to rear wheels in a manner to be suspended downward from a vehicle body.
However, a part of the ladder of the wheel loader, which is suspended downward below a departure-angle-defining line connecting a ground touching portion of each of the rear wheels and a lower surface of a counter weight near the back of the vehicle, may be damaged by contact with the ground when a front of the vehicle body is inclined upward during a scraping operation while climbing a mound.
The ladder disclosed in Patent Literature 1 includes: an upper step board having a fixed step board portion disposed near the front of the vehicle and a rotary step board portion that is connected in a pivotally movable manner to the fixed step board portion and is disposed near the back of the vehicle; an elastically deformable first suspension member, an upper end of which is connected in a pivotally movable manner to a front end of the fixed step board portion; an elastically deformable second suspension member, an upper end of which is connected to a rear end of the rotary step board portion; and a lower step board that is connected in a pivotally movable manner to the first and second suspension members.
With this arrangement, when the lower step board comes into contact with the ground during the scraping operation, the lower step board receives external force to be pushed backward. At this time, the lower step board pivots on the first and second suspension members, the first and second suspension members pivot on the fixed step board portion and the rotary step board portion, and the rotary step board portion pivots upward on the fixed step board portion. Accordingly, the entire ladder is folded and received between a fixing portion of the ladder to the vehicle body and the ground, in other words, above the departure-angle-defining line in alignment with the ground, so that damage to the lower step board and the like can be prevented.
On the other hand, Patent Literature 2 discloses a large-sized hydraulic excavator having a ladder in the front of the vehicle body. Patent Literature 2 proposes providing a further step to a lower end of the ladder. The ladder is for the operator to climb up and down from the front of the vehicle. The ladder is configured in a four-link mechanism in which two parallel links are suspended in a pivotally movable manner in a vehicle front-back direction from one of side plates in a vehicle width direction of the ladder, two parallel links are suspended in a pivotally movable manner also from the other of the side plates in the vehicle width direction, and a step board is provided in a pivotally movable manner to the parallel links provided apart in the vehicle width direction.
Also in such a configuration of the ladder, when the vehicle sinks below a surface of a soft ground due to its own weight to cause a lower end of the ladder to contact with the ground, the step board pivots on lower ends of the parallel links to move upward, so that damage to the step board and the like can be prevented. Moreover, since the ladder is additionally attached to the lower end of the ladder and the step board is close to the ground, the ladder can facilitate access to the ladder from the ground.